LeetCode/226_Invert_Binary_Tree.py at main · AnmolPatel20/LeetCode · GitHub

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"""
Given the root of a binary tree, invert the tree, and return its root.


Example 1:


Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
Example 2:


Input: root = [2,1,3]
Output: [2,3,1]
Example 3:

Input: root = []
Output: []


Constraints:

The number of nodes in the tree is in the range [0, 100].
-100 <= Node.val <= 100

"""

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
        if not root:
            return None

        #swap the children
        temp = root.left
        root.left = root.right
        root.right = temp

        self.invertTree(root.left)
        self.invertTree(root.right)
        return root